Inflammatory bowel diseases (IBO), which include Crohn's disease (CD) and ulcerative colitis (UC), are chronic immune-mediated conditions of the digestive system that affect an estimated 1.4 million Americans of all ages, races and ethnicities. Time trends in both industrialized and developing countries suggest rising incidence and prevalence worldwide. Epidemiologic data are scarce, however, in the United States, given-the lack of a national healthcare system and of a readily available population sampling method for disease surveillance. The conditions generally relapse and remit unpredictably with symptomatic flares that may include diarrhea, abdominal pain, rectal bleeding, fatigue, weight loss, and a variety of complications and extra-intestinal manifestations, including developmental effects in children. Medications are used to control symptoms and prevent progression by diminishing inflammatory and immune responses, while surgery may be needed to treat disease complications. The personal impact of IBO varies widely among individuals, however, and likely reflects individual differences in disease biology, variations in the timing and choice of therapies, and disparate psychosocial and economic characteristics. Understanding the impact of IBO on affected individuals, and the biological, medical and psychosocial determinants of that impact, is critical if individual outcomes are to be improved through rationally designed interventions. In addition, if a national surveillance program for IBO could be created, disease trends in the US could be tracked, with appropriate dedication of resources to meet the population's needs. The Crohn's & Colitis Foundation of America (CCFA) is the nation's largest non-profit organization devoted to lBO, with robust lay and professional involvement. Through advocacy, research grants and initiatives supported through its own fundraising efforts, and a long-standing collaboration with the CDC through earlier U01 research cooperative agreements, the CCFA has been working to achieve an improved understanding of the epidemiology of IBO and the basis of disease heterogeneity as a means of improving outcomes. The overarching goal of this proposal is to identify the population health needs of individuals afflicted with lBO, and to design and implement interventions to improve their disease outcomes. This proposal leverages the unique assets of the CCFA to address key issues in the epidemiology and outcomes of IBO. These include coordination and involvement of lay stakeholders; an active National Scientific Advisory Committee with Professional Affairs and Patient Education Committees dedicated to creating and disseminating significant interventions; a website and a variety of other avenues to channel information to patients and providers; CCFA Partners, a novel online cohort of patients with self-reported disease outcomes, and OSCCAR (the Ocean State Crohn's and Colitis Area Registry), a unique, community-based prospective IBO inception cohort created through the CCFA's work with the CDC over the last 5 years.